Date post: | 05-Apr-2018 |
Category: |
Documents |
Upload: | bwade2916499061 |
View: | 214 times |
Download: | 0 times |
of 36
7/31/2019 Hormones and Nutrient Partitioning
1/36
Hormones and nutrient
partitioning
Dr. Mark Meade
7/31/2019 Hormones and Nutrient Partitioning
2/36
7/31/2019 Hormones and Nutrient Partitioning
3/36
Control of nutrient utilization
Nutrient utilization controlled by metabolicpathways and metabolites themselves but
are primarily controlled by hormones Hormonea chemical messenger produced in
the body by one tissue that effects the actions ofother tissues
Many hormones involved in partitioning theuse of energy to those areas where its neededin the body
7/31/2019 Hormones and Nutrient Partitioning
4/36
7/31/2019 Hormones and Nutrient Partitioning
5/36
7/31/2019 Hormones and Nutrient Partitioning
6/36
7/31/2019 Hormones and Nutrient Partitioning
7/36
Insulin and Glucagon
Produced by (glucagon) and (insulin) cells of
pancreas
Insulin released in response to high blood glucose Also in response to glucagon, GH, and gastric
inhibitory peptide (glucose-dependent insulin-releasing
peptide)
Glucagon released in response to low bloodglucose
7/31/2019 Hormones and Nutrient Partitioning
8/36
7/31/2019 Hormones and Nutrient Partitioning
9/36
Insulin
Overall, makes sure cells can take up nutrients
(glucose)
Increases rate of uptake of glucose by liver, muscle andfat cells
Stimulates glycogenesis (formation of new glucose)
Stimulates release of fatty acids from liver and fat
Stimulates uptake of amino acids by liver and muscle
7/31/2019 Hormones and Nutrient Partitioning
10/36
Abnormalities associated with
insulin Diabetes mellitus (type I)associated with
a loss of cells in pancreas (autoimmune)
Diabetes mellitus (type II)associated with
defective signal reception for insulin
Both lead to hyperglycemia, glycosuria, and
reduced stores of lipids and proteins
7/31/2019 Hormones and Nutrient Partitioning
11/36
Growth Hormone (GH or
somatotropin) Produced by anterior pituitary
Release controlled by two hypothalamic
neurohormones
GH releasing hormone (GRH)
GH inhibiting hormone (GIH or somatostatin)
Blood glucose can effect release of
hypothalamic hormones
7/31/2019 Hormones and Nutrient Partitioning
12/36
7/31/2019 Hormones and Nutrient Partitioning
13/36
GH
Increases blood glucose by
Stimulating gluconeogenesis
Blocking glucose uptake by tissues other than
nervous system
Promotes utilization of fatty acids as an energy
source Promotes use of other substrates than glucose
7/31/2019 Hormones and Nutrient Partitioning
14/36
GH functions
Promotes RNA and protein synthesis
Promotes growth of bone and cartilage
Promotes growth by increasing cell
numbers
7/31/2019 Hormones and Nutrient Partitioning
15/36
Response to GH
Depends on age of animal
Neonatal mammal is insensitive
Stimulates liver to produce other growth-
promoting factors (insulin-like growth
factors)
7/31/2019 Hormones and Nutrient Partitioning
16/36
GH abnormalities
Gigantismcaused by hypersecretion of
GH before puberty
Acromegalycaused by hypersecretion of
GH after puberty
Dwarfismcaused by by hyposecretion of
GH during childhood and adolescence
7/31/2019 Hormones and Nutrient Partitioning
17/36
IGF
Insulin-like growth factors
Many different forms produced by many tissues
IGF-I produced by liver
IGF-I mediates the effects of GH on tissues
Helps GH cause muscle growth
Independently reduces uptake of glucose by fat cells
7/31/2019 Hormones and Nutrient Partitioning
18/36
Catecholamines and
Glucocorticoids Adrenal gland
hormones
Catecholamineadrenal medulla
(ectodermal origin)
Glucocorticoids
adrenal cortex(mesodermal origin)
7/31/2019 Hormones and Nutrient Partitioning
19/36
Chromaffin cells
(modifiedpostganglionicsympathetic neurons)
7/31/2019 Hormones and Nutrient Partitioning
20/36
Synthesis and release of
catecholamines Both a neurotransmitter and hormone
Involved in famed fight or flight response
As a hormone, acts to: Cause contraction/relaxation of smooth muscle
Stimulate glycolysis and lipolysis
Increase heart rate and contraction Known to increase muscle production and
decrease stored lipid
7/31/2019 Hormones and Nutrient Partitioning
21/36
Chromaffin cells
Found with steroidogenic tissues in
mammals
Significance is steroidogenic tissue inducesproduction of more epi than nor-epi
Found as separate tissue in other vertebrates
(e.g., fishes)
7/31/2019 Hormones and Nutrient Partitioning
22/36
Epi and Nor-epi release
Chromaffin cells
stimulated by action of
preganglionicsympathetic nerves
7/31/2019 Hormones and Nutrient Partitioning
23/36
Pos and Neg feedback
Release of epi causes more blood flow to adrenals
and thus more release of epi (pos)
Release of nor-epi inhibits further release of nor-epi (neg)
ATP (in secretory granules) reduces calcium
influx and thus inhibits release (neg)
Hypoxia can also stimulate release of
catecholamines (pos)
7/31/2019 Hormones and Nutrient Partitioning
24/36
Effects of catecholamines
Many effects depending on the type of adrenergic
receptors (adrenoreceptors)
-increase metabolic rate and blood flow - increase blood glucose and fatty acid conentrations
Also stimulate protein synthesis in muscle and lipolysis in
adipose (fat) tissue
Thus stimulation of receptors will enhance growth
Ractopaminea agonist used in pigs and cattle to
stimulate increased muscle
7/31/2019 Hormones and Nutrient Partitioning
25/36
Glucocorticoids
Released from adrenal cortex when
stimulated by the anterior pituitary hormone
ACTH 3 categories actually secreted
Glucocorticoids
Mineralcorticoids
Reproductive hormones
7/31/2019 Hormones and Nutrient Partitioning
26/36
Glucocorticoids
Cortisol
Cortisone
corticosterone
7/31/2019 Hormones and Nutrient Partitioning
27/36
7/31/2019 Hormones and Nutrient Partitioning
28/36
CRH release
Glucocorticoid levels highest in morning
Starvation
Stress
7/31/2019 Hormones and Nutrient Partitioning
29/36
Glucocorticoid effects
Liver
Promotes gluconeogenesis
Fat cells Release fatty acids (direct source of energy)
Muscle cells
Lose amino acids (opposite the effects of
catecholamines) Also stimulate gastric secretion, inhibit immune
response
7/31/2019 Hormones and Nutrient Partitioning
30/36
Thyroid hormones
Cells (follicles) of thyroid are stimulated by
TSH from anterior pituitary
Two major thyroid hormones
3,5,3-triiodothyronine (T3)
Thyroxine (T4)
Steroid-like hormones which have longlasting effects on target cells
7/31/2019 Hormones and Nutrient Partitioning
31/36
7/31/2019 Hormones and Nutrient Partitioning
32/36
7/31/2019 Hormones and Nutrient Partitioning
33/36
Effects of thyroid hormones on
target tissues Causes organs to be more sensitive to
epinephrine, stimulating cellular respiration,
oxygen consumption, and metabolic rate
Affect development and maturation of some
mammals (protein synthesis)
Only in presence of GH
7/31/2019 Hormones and Nutrient Partitioning
34/36
Thyroid abnormalities
Cretinism (humans)results from
hypothyroidism (lack of dietary iodine)
Somatic, neural, and sexual development
Metabolic rate reduced
Immune responses limited
Hypothalamus continues to secrete TSH andcauses thyroid gland to hypertrophy (goiter)
7/31/2019 Hormones and Nutrient Partitioning
35/36
Leptin
A hormone produced by fat tissue
A satiety hormone that plays role in
regulating appetite.
Acts as a body fat sensor
Increased in body when fats high thus decreasing
appetite Decreased in body when fats low thus increasing
appetite
7/31/2019 Hormones and Nutrient Partitioning
36/36
Regulation of milk production
Can require huge amounts of energy and animalwill sacrifice nutrients to make sure lactationoccurs properly
Controlled by GH, IGF-I, and estrogen (an ovary
hormone) in ruminants Controlled by prolactin (another pituitary
hormone) and estrogen in non-ruminants
Insulin may have some stimulatory effect since itresults in glucose availabiltiy
Glucocorticoids may inhibit lactation
Thyroid hormones may also stimulate lactation